Marcinkiewicz CH 307FL vs Marcinkiewicz CH 5FLD
The Marcinkiewicz CH 5FLD has a wider cup diameter, the Marcinkiewicz CH 307FL features a deeper cup.
Cup Diameter
The Marcinkiewicz CH 5FLD has a cup diameter of 17.25 mm / 0.6791 in compared to 17.20 mm / 0.6772 in on the Marcinkiewicz CH 307FL — a difference of 0.05 mm / 0.0020 in. A wider cup generally produces a fuller, darker tone but requires more air support.
Cup Depth
The Marcinkiewicz CH 307FL has a very deep cup while the Marcinkiewicz CH 5FLD has a deep cup. Deeper cups favor a darker, richer sound; shallower cups provide more brightness and easier upper register.
Throat Diameter
Throat diameters are essentially identical at 4.32 mm / 0.1701 in, so resistance feel will be comparable.
Which is better?
Neither mouthpiece clearly dominates the other — the right choice depends on your embouchure, playing style, and the sound you're after. Try both if possible.